Beryllium cobalt alloy steels and articles of manufacture produced therefrom



Patented Aug. 14, 1945 BERYLLIUM OOBAL'I. ALLOY STEELS AND ARTICLES OF MANUFACTURE PRODUCED THEREFBOM Enrique G. Touoeda and Ralph P. De Vriea, Albany, N. Y., asslgnors to Allegheny Ludlum Steel Corporation, a corporation of Pennsylvania No Drawing. Application July 28, 1942,

Serial No. 452.637

- 13 Claims.

Our present invention relates to tool steels, die steels and structural steels and more particularly to beryllium-containing alloy steels and to various tools, dies and structural members produced therefrom.

The hardening of steels is well-known and extensively practiced and the particular hardening procedure depends upon the composition undergoing hardening as well as upon the intended use of that material. In general, hardening procedures require heating the material to a rather high temperature in order to set the maximum degree of hardness and this heat treatment is followed by quenching in oil or by air-hardening. Some alloys are hardened in the as cast condition, whereas others are hardened only after they have been forged. For some dies and tools it is necessary or desirable to employ a. composition which contains a relatively high percentage of chromium because such decarburize less in long heating cycles and retain a better surface because of their scale-resisting qualities. This is particularly advantageous where steel is to be cast di-- rectly into final form and shape, requiring grindlng only on the edges or faces where the dies or tools have to perform a cutting, forming or other shaping function. Many steels do not harden well or acquire the requisite degree of hardness and in some cases also careful adjustment must be made in the analysis of the steel because some elements counteract others wholly or in part particularly with respect to the ability of the steel to be hardened. There is, therefore, a somewhat unsatisfactory situation surrounding the hardening of various types of alloys and steels and as a result satisfactory compositions are relatively dilflcult and expensive to produce.

One of the objects of our present invention is to produce alloy steels of the character hereinafter defined which not only have highly desirable properties but which are also readily hardenable in a comparatively simple and inexpensive manner.

Another object of our invention is to produce beryllium-containing alloy steels which have properties of hardenability and other physical properties which admirably adapt the same for use in tools, dies and various structural members or parts.

A further object of our invention is to produce beryllium containing alloy steels wherein the beryllium content, in conjunction with the other constituents of these steels. has a definite beneficial effect upon the ability of these compositions to be hardened.

A still further object of our invention is to produce alloy steels containing, in addition to iron and the usual impurities in common amounts, about .10-33% of carbon, about .5-14% of chromium, about 35-35% of manganese, about .5-3% of molybdenum, about 25-25% of copper, about .101% of cobalt, about .15-2% of silicon and about .05-.3% oi beryllium, such steels being characterized by the fact that they can be hardened at a temperature materially below that heretofore employed in connection with prior compositions and by the retention of their acquired hardness at a much higher drawing temperature than was possible with such prior compositions.

Other and further objects and advantages will be understood by those skilled in this art or will be apparent or pointed out hereinafter.

The property of hardness, in the sense in which that term is ordinarily employed, is wholly relative and it therefore is essential to obtain a more accurate appreciation of the significance of meaning of hardness in order that our present invention may be properly understood and evaluated. While it is a fact that hardness is based upon a comparison with familiar materials which are used as a convenient yardstick, we wish to point out that hardness and size are interrelated in such manner that unless the size of a product or article is taken into account the hardening effect of a given procedure cannot be definitely evaluated.

so For example, and by way 01' explanation, those steels which have to be hardened for tool and die purposes to give them hardness values equivalent to 600 Brinell or more are definitely limited as to sizes which can be hardened by a given procedure. Hence, if a 1" round of a 1% carbon steel is heated to the proper temperature and quenched in water it will harden to the fullest possible extent, but if the size of the piece is increased the degree of hardness produced in it by an identical treatment becomes progressively less until a size is reached where the hardening eiiect is entirely inadequate. Steels which are oil-hardening and which can be hardened to at least 600 Brlnell and cone Rockwell are subject to the same limitations, namely, that as the size increases the hardening effect diminishes. This is also true of the lmown air-hardening steels and to those particular air-hardening steels which are included in the tables forming a part thereof. In many cases it is, therefore, essential to know the sire Or the dimensions of the product or article in order that the quality of hardness may have definite significanoe.

Our present invention is predicated upon the discovery that alloy steels of the compositions here included have new and highly desirable as well as unexpected properties and characteristics by virtue of their beryllium content in conjunction with the remaining elements in the amounts specified. Such steels are not only readily hardenable to a desired degree of hardness either in the as cast condition or alter forging, but that hardness can be obtained at a materially lower temperature than a comparative degree of hardness can be imparted to prior (beryllium-free) compositions. Even relatively very small amounts of beryllium show hardening advantages characteristic of our new steels; that is to say, the factor of hardenability is favorable even when the steels contain amounts of constituents in the lower portions of the ranges specitled. In addition, good hardness characteristics can be secured throughout the entire ranges of the compositions recited, except that within the limitations subsequently set forth the precaution should be observed that the manganese and silicon contents should not be simultaneously in the upper portions 01 their respective ranges. The ability to impart the'desired hardness at a lower than usual temperature is highly advantageous and represents a considerable saving in the cost of hardening.

tion 2" square. It will be observed from this table that after air cooling from 1450 F. the compositions containing beryllium were hard whereas those without beryllium were soft which clearly signifies that the beryllium-containing compositions hardened satisfactorily but that the beryllium-free compositions did not. Attention is further directed to the fact that composition 6-84 and (356 contain all the elements of compositions 6-63 and 6-55 except beryllium and that composition 6-57 lacks both copper and beryi lium. Thus it will be appreciated that the desirable hardenable character of compositions such as 6-53 and 6-55 can be attributed to their beryllium or beryllium-copper content in conjunction with the other constituents. The extra addition of nickel in composition 6-61 had no great eifect upon the hardness as can be noted from the table.

In Table II, which follows, we have set forth hardness data concerning a number of alloy steels which were all hardened in the as cast condition and in that table the sizes of the castings are specified for reasons which will be appreciated from what has preceded:

Table II 5 NNNPFF=. PPFFPPP ssssssgssssssss assess-assass ns sssssssss sssssssss Our invention accordingly comprises those alloy steels which contain, in addition to iron and the usual impurities in common amounts, about .10-8% of carbon. about .5-14% of chromium about .753.5% of manganese, about .5-3% of 45 Table I [Forglngsz 3" in length, 2" square] From this table it will be noted that the hardness indicated was produced by heat treatments at low temperatures ranging from 1450 to 1550 R, followed by air cooling, and that althcu zh the dimensions of the castings varied considerably the hardness of all the beryllium-containing compositions is consistently higher and markedly superior to the beryllium-free compositions. By comparing compositions A-l88 and A-189, it will be further noted that the hardening advantages of our new compositions are obtained even where the percentage of copper and of beryllium is each near the lower part of its respective range. The ability to obtain a desired extent oi hardening substantially independently of even rather material variations in size is a tremendous commercial and economic advantage which not only simplifies Mt Hardness Melt No. 0 Cr Si Mn Mo Ni Be On cooled C fromone Brinell We File OF. .30 1. 49 1. 12 1.52 1.02 0. 05 1.34 l, 450 601 63 Hard. 28 l. 54 l. 05 l. 45 .96 h-.. 05 l. 30 1,450 601 01 Do. 39 1. 54 .59 1.83 05 l, 450 444 El. 5 Soft. .20 1.55 1.02 1.58 .62 0.32 .IO .95 1,450 627 52 Hard. 6- .38 1.55 .2! 1.50 .67 1,450 .m Soft. 6-56 1.45 1.56 1.02 1.57 .91 1. 28 1,450 514 55.5 Do.

All the steels in Table I were forged to the same size, namely to 3" in length and to a cross setthe hardening procedure and renders it much less expensive but that hardening procedure can be 2,ssa,oso

standardized with the further advantages flowing therefrom.

For certain die and tool purposes it is important to include as much chromium as possible in the steel for the reason that the long heating cycles which are involved in connection with certain production procedures eflects less decarburlsation and in addition the steels retain a better surface because their scale resistance is high, whereas neither would be the casein connection with relatively ,low chromium contents. As already indicated above, good resistance to decarburiaation and to scaling is especially desirable where such steel is to be cast in its ultimate form and shape save onw for grinding on the edges or laces where, in the case of dies, a cutting, shaping or analogous function must be performed.

Known air-hardening die steels containing a high content, c. g., about 12% of chromium, about 1.5 to 2% of carbon, plus molybdenum and cobalt, must be hardened from high temperatures ranging from about 1800 to 1900' I". Table II shows that a 12% chromium steel (A424) having the composition specified in the last line of the table can be satisfactorily hardened when heated to 1450-1550 I". and air cooled, but in connection with this particular composition and this type of chromium steel (see also A454) the manganese and silicon contents must both be kept below the upper limits of the ranges set forth above in order to obtain this desirable result; whereas in connection with the use of an amount of chromium in the lower part of the specified chromium range an amount of manganese may be employed as high as 3.5%. The amount of manganese must be reduced to a maximum of about 2.75%. when the amount of chromium approaches the upper part of its range, in order to obtain maximum effective hardening and furthermore if the size of the die permits the maximum manganese content should not exceed a maximum of 1.75%. Under these conditions the silicon content must also be kept low, i. e., .5% or less. The last four compositions in the table exemplify these principles.

From the loregoing it will be seen that hardening can be carried out on our new alloy steels with the use of a temperature about 400 F. lower than that which is used with other types of air hardening high chromium steels. This represents a considerable saving in the cost of the hardening operation even though the heating cycle to obtain a solid solution and the subsequent hardening may be the same. Our new steels have a fineness of grain structure which is equal or superior to prior compositions as determined by micrographic and macrographic examination, little difference being noted between those steels which are hardened in the as cast condition without being subjected to forging and those which have been previously forged. Our new steels can be cast to form and shape with extremely good fluidity characteristics in which connection the high carbon content acts to lower the melting points and the beryllium content markedly increases fluidity.

Characteristics such as those enumerated are valuable in facilitating the production of numerous articles which would otherwise be difllcult or costly to produce: for example, thin-walled cylinders can be made in a simple manner by casting cylinders having a slightly heavier thickness wall than that desired by any known casting procedure and then slightly reducing the wall thickness to that ultimately desired by means of a forging or machining operation or both. In some casesnnalsizemaybeobtaineddirectlybycasting alone. Automotive and airplane cylinder sleeves, slush pump liners and many other articles can be thus easily made and with great savings in cost. We wish it to be understood that in making thin-walled articles or articles having a smalltotal massitisnotnecessarytousethe maximum amounts of the individual elements listed above because in these lighter sections the lower percentages of these elements will enable the articles to be hardened suiliciently. In other words, steels which are normalized and then reheated to high but sub-critical temperatures are suiilciently hard for many applications.

Where the carbon content of our new alloy steels is in the lower portion of its range, for example, from about .10 to 50%, such steels can be carburined on their outside surfaces and air hardened from a temperature of about 1450 F. after the "case" of the steels has been raised by the carburizing operation to a carbon content in the neighborhood of 1%. These steels possess certain advantages over ordinary carburizing steels in that they maintain or retain their hardnose at a much higher drawing tem erature than Carburized in Homocarb furnace for 4 hours at 1650" F'. followed by slow cooling.

From as carburlzed:

i hr.--i,450 F. air

Rockwell A Rockwell C File 82. 5/83 02. 5/64 H. 82/83 63/64 H. SID/8i 00/61 B. 81/81. is 59/60 H.

79/80 57/58 Resistant 79/79 54/66 D0 The Rockwell A values show that the case" is as hard as that of a nitrided steel and that hardness does not decrease appreciably until a drawing temperature of 700 i reached. Because of the fact that the medium carbon steels when carburized can be quenched in air and do not have to be quenched in oil or water they can be carburized without any danger of cracking or undue distortion in the subsequent quenching operation.

As we have stated above, where comparatively small sections are to be hardened the amounts of the various alloying elements can be well below the upper limits specified. These alloys can be hardened in oil in those cases in which deformation during hardening need not be too particularly considered. Where alloy steels responding to our present invention involve the use of the lower amounts of the alloying elements set forth it will be found that these steels when cast have particularly good ductility without resorting to those heat treatments which are ordinarily carried out on cast sections. Thus our alloys in comparatively small sections may be pressure cast or still cast to desired form or shape and afterwards hardened directly with or without a sub-critical anneal.

Cast steels responding to our present invention containing as little as .10% carbon and an amount of chromium which is in the lower or middle portion of the specified chromium range possess, when quenched, very high transverse fibre stress with a ductility equal to a 50 or greater bend. Cast steels in these carbon and chromium ranges can be quenched in oil through a range of 1450 to 1850 F. without any previous anneal or normalizing treatment. Examples 01 such cast steels which have outstanding tensile properties are included in Table IV which follows:

assaoso balance being substantially all iron except for the usual impurities in common amounts.

4. A beryllium modified chromium tool and die steel containing about 12% of chromium, an amount 01 beryllium up to about .3% plus small amounts of molybdenum and cobalt and not more than about 2.75% manganese, said steel being characterized by the fact that it can be hardened from abnormally low temperatures as compared with a like steel free from beryllium.

5. A hardened article 01 manufacture having a hardness value of at least 600 Brlnell and 60 cone Table IV (All alloys as east plus heat treatment indicated] Yield Tensile Point Strength Elong. Red. Melt C Cr Si Mn Mo Cu Be State Brinell per cent area,

in 2 per cent P. s i P. s. i. I

A431... 0.10 7.50 0.50 3.25 0.60 0.50 0.05 air-1,760 F. 01] drawn 352/375 150, 000 184,000 7.5 23.0 1,7so r. oil-drawn 1,350 r. air 51,000 120,000 10. as. s l,500 F. air-drawn 750 F. air 110, 000 174,000 8. 0 Zi. l Ai41.... .10 8.50 .75 3.25 1.00 .60 .05 1,700 F. 011 drawn 750alr 415 111,000 205,000 4.0 9.2 A442... .10 8.50 .75 2.75 .50 .75 .05 1,750" F.0il drawn 750 air. 109,000 5.5 17.2 A441... .10 8.50 .50 3.25 .26 .50 .10 1,750 F.0ll drawn'lfifl air ,000 2.5 6.0

a It will be understood that it such steels are Rockwell which is produced by heat treating carburized and subsequently hardened from low air hardening temperatures of 1450 or thereabouts, the core of such steels will exhibit a duotility which is equal to or better than any cast steels or which we have knowledge. Should it be desired merely to produce a cast structure with a very hard surface and good ductility this can be accomplished by heat treatment in a liquid carburizing bath at temperatures of about 1550 F. directly followed by quenching. We again caution against the concurrent use 01 high silicon and high manganese in conjuction with the low carbon and the low and medium chromium ranges of compositions set forth above.

It will be understood that the ioregoing is illustrative and not limitative and that various additions, omissions, substitutions and modifications may be made therein without departing from the spirit and scope of our invention as defined by the appended claims.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. An alloy tool and die steel containing from about .50 to about 14.00% of chromium, from about .10 to about 1.00% of cobalt, from about .05 to about 30% of beryllium and from about .25 to about 2.50% copper.

2. An alloy steel capable of being hardened to a value of at least 600 Brinnell and which, in addition to iron and the usual impurities in common amounts, consists of about .l-3% carbon, about .514% chromium, about .'I5-3.5% manganese, about .5-3% molybdenum, about .l-l% cobalt, about .l5-2% silicon, about -25% copper and about 05-23% beryllium.

3. An alloy steel which is characterized by the fact that it can be hardened from a temperature ranging from about l450-1550 F, by exceptional fluidity when in the molten state and by the capacity of being cast to final shape and dimensions, said alloy steel being composed of about .1-3% carbon, about .5-14% chromium, about .75-3.5% manganese, about .5-3% molybdenum, about .l-l% cobalt, about .l5-2% silicon, about 25-25% copper, about .05-.3% beryllium, the

within the range of about l450-1550 F. and then air-cooling a composition consisting oi the following constituents in approximately the following amounts, the balance being substantially all iron except for the usual impurities in common amounts:

Percent Carbon .l -3 Chromium .5 -14 Manganese .75-3.5 Molybdenum .5 -3 Cobalt .1 -1 Silicon .15-2 Copper .25-25 Beryllium .05- .3

6. An alloy steel characterized by the fact that it can be hardened to a value in excess of 600 Brinell and 60 cone Rockwell from a temperature as low as about 1450 F. which, in addition to iron and the usual impurities in common amounts. consists of about 1.3% of carbon, about 1.5% of chromium, about 1.1% of silicon. about 1.5% of manganese, about 1% of molybdenum, about 1.3% of copper and a small amount of beryllium oi the order of about .05-.1%.

7. An alloy steel characterized by its capacity to be hardened to a value in excess of 600 Brinell and 60 cone Rockwell by a heat treatment at about 1500" F. and air-cooling in the as cast condition which consists of about 2% carbon. about 12% chromium, about .5% silicon, about 2% manganese, about 1% molybdenum, about 1.3% copper and a small amount of beryllium oi the order of .05-.1%, the balance being substantially all iron except for the usual impurities in common amounts.

8. A beryllium alloy steel forging which, in a piece 2" square by 3" in length, can be hardened to a value in excess of 600 Brinell and 60 cone Rockwell by air cooling after heat treating at a temperature as low as about 14500 F. and which is composed of an air hardening chromium steel in which has been incorporated about .25-2.5% copper and about .05-.3% beryllium.

9. An alloy steel of the character defined by claim 3 characterized by the fact that the same can be hardened to a value in excess of 600 Brinell and 60 cone Rockwell even when the constituents thereof are present in the middle and lower portions of their respective ranges.

10. An alloy steel of the character defined by claim 3 characterized by the fact that the same can be hardened to a value in excess of 600 Brinell and 60 cone Rockwell even when the constituents thereof are present in the middle and lower portions of their respective ranges, the manganese and silicon contents thereof being correlated with the chrominum content in such manner that the maximum amount of manganese specified may be present when the chromium content is in the lower portion of its range but not more than approximately 2.75% when the chromium is in the upper portion of its range.

11. An air hardening tool steel containing. among other alloying constituents, chromium within the range of from 0.50% to 14.00%, molybdenum within the range of from about 0.50% to about 3.00%, copper within the range oi from about 0.25% to about 2.5% and beryllium within the range of from about 0.05% to 0.30% and characterlzed by hardening at relatively low temperatures in the as cast and in the worked form, and of retaining its hardness at a higher temperature of draw than ordinary tool steels.

12. An air hardening die and tool steel having a chromium content in the neighborhood of 12%, substantial amounts of molybdenum and cobalt, carbon in the range of from about 1% to about 2%, copper within the range of from about 0.25% to 2.25% and beryllium within the range of from about 0.05% to about 0.30% and characterized by hardening at temperatures from about 1450 F. to 1550 F. in either the as cast or worked form when cooled in air.

13. An air hardening steel containing, among other alloying constituents, carbon from about 0.10% to about 0.60%, chromium from about 3% to about 14% and copper and beryllium together within the range of from about 0.50% to about 0.00% and characterized by air-hardening from a temperature of about 1450 F. after carburizing to raise the carbon content of the case by about 1%.

ENRIQUE G. TOUCEDA. RALPH P. DE VRIE'S.

CERTIFICATE OF CORRECTION.

Patent No. 2.382.680.

August ILL, 1914.5

ENHIQUE G. TOUCEDA, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Pagel first column, line 56, claim 1, for read -.50%--; 0 ".05-5?!" read -.05-.5%--; and second column, line 71, for "11.0500

line 65, claim 2, for

read

-1l 50-; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case intho Patent Office Signed and sealed this 11th day of December, A. D. 1915.

(Seal) Leslie Frazer First Assistant Commissioner of Patents.

claim 3 characterized by the fact that the same can be hardened to a value in excess of 600 Brinell and 60 cone Rockwell even when the constituents thereof are present in the middle and lower portions of their respective ranges.

10. An alloy steel of the character defined by claim 3 characterized by the fact that the same can be hardened to a value in excess of 600 Brinell and 60 cone Rockwell even when the constituents thereof are present in the middle and lower portions of their respective ranges, the manganese and silicon contents thereof being correlated with the chrominum content in such manner that the maximum amount of manganese specified may be present when the chromium content is in the lower portion of its range but not more than approximately 2.75% when the chromium is in the upper portion of its range.

11. An air hardening tool steel containing. among other alloying constituents, chromium within the range of from 0.50% to 14.00%, molybdenum within the range of from about 0.50% to about 3.00%, copper within the range oi from about 0.25% to about 2.5% and beryllium within the range of from about 0.05% to 0.30% and characterlzed by hardening at relatively low temperatures in the as cast and in the worked form, and of retaining its hardness at a higher temperature of draw than ordinary tool steels.

12. An air hardening die and tool steel having a chromium content in the neighborhood of 12%, substantial amounts of molybdenum and cobalt, carbon in the range of from about 1% to about 2%, copper within the range of from about 0.25% to 2.25% and beryllium within the range of from about 0.05% to about 0.30% and characterized by hardening at temperatures from about 1450 F. to 1550 F. in either the as cast or worked form when cooled in air.

13. An air hardening steel containing, among other alloying constituents, carbon from about 0.10% to about 0.60%, chromium from about 3% to about 14% and copper and beryllium together within the range of from about 0.50% to about 0.00% and characterized by air-hardening from a temperature of about 1450 F. after carburizing to raise the carbon content of the case by about 1%.

ENRIQUE G. TOUCEDA. RALPH P. DE VRIE'S.

CERTIFICATE OF CORRECTION.

Patent No. 2.382.680.

August ILL, 1914.5

ENHIQUE G. TOUCEDA, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Pagel first column, line 56, claim 1, for read -.50%--; 0 ".05-5?!" read -.05-.5%--; and second column, line 71, for "11.0500

line 65, claim 2, for

read

-1l 50-; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case intho Patent Office Signed and sealed this 11th day of December, A. D. 1915.

(Seal) Leslie Frazer First Assistant Commissioner of Patents. 

